sfi-cpufreq.c 3.1 KB

123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899100101102103104105106107108109110111112113114115116117118119120121122123124125126127
  1. // SPDX-License-Identifier: GPL-2.0-only
  2. /*
  3. * SFI Performance States Driver
  4. *
  5. * Author: Vishwesh M Rudramuni <vishwesh.m.rudramuni@intel.com>
  6. * Author: Srinidhi Kasagar <srinidhi.kasagar@intel.com>
  7. */
  8. #include <linux/cpufreq.h>
  9. #include <linux/init.h>
  10. #include <linux/kernel.h>
  11. #include <linux/module.h>
  12. #include <linux/sfi.h>
  13. #include <linux/slab.h>
  14. #include <linux/smp.h>
  15. #include <asm/msr.h>
  16. static struct cpufreq_frequency_table *freq_table;
  17. static struct sfi_freq_table_entry *sfi_cpufreq_array;
  18. static int num_freq_table_entries;
  19. static int sfi_parse_freq(struct sfi_table_header *table)
  20. {
  21. struct sfi_table_simple *sb;
  22. struct sfi_freq_table_entry *pentry;
  23. int totallen;
  24. sb = (struct sfi_table_simple *)table;
  25. num_freq_table_entries = SFI_GET_NUM_ENTRIES(sb,
  26. struct sfi_freq_table_entry);
  27. if (num_freq_table_entries <= 1) {
  28. pr_err("No p-states discovered\n");
  29. return -ENODEV;
  30. }
  31. pentry = (struct sfi_freq_table_entry *)sb->pentry;
  32. totallen = num_freq_table_entries * sizeof(*pentry);
  33. sfi_cpufreq_array = kmemdup(pentry, totallen, GFP_KERNEL);
  34. if (!sfi_cpufreq_array)
  35. return -ENOMEM;
  36. return 0;
  37. }
  38. static int sfi_cpufreq_target(struct cpufreq_policy *policy, unsigned int index)
  39. {
  40. unsigned int next_perf_state = 0; /* Index into perf table */
  41. u32 lo, hi;
  42. next_perf_state = policy->freq_table[index].driver_data;
  43. rdmsr_on_cpu(policy->cpu, MSR_IA32_PERF_CTL, &lo, &hi);
  44. lo = (lo & ~INTEL_PERF_CTL_MASK) |
  45. ((u32) sfi_cpufreq_array[next_perf_state].ctrl_val &
  46. INTEL_PERF_CTL_MASK);
  47. wrmsr_on_cpu(policy->cpu, MSR_IA32_PERF_CTL, lo, hi);
  48. return 0;
  49. }
  50. static int sfi_cpufreq_cpu_init(struct cpufreq_policy *policy)
  51. {
  52. policy->shared_type = CPUFREQ_SHARED_TYPE_HW;
  53. policy->cpuinfo.transition_latency = 100000; /* 100us */
  54. policy->freq_table = freq_table;
  55. return 0;
  56. }
  57. static struct cpufreq_driver sfi_cpufreq_driver = {
  58. .flags = CPUFREQ_CONST_LOOPS,
  59. .verify = cpufreq_generic_frequency_table_verify,
  60. .target_index = sfi_cpufreq_target,
  61. .init = sfi_cpufreq_cpu_init,
  62. .name = "sfi-cpufreq",
  63. .attr = cpufreq_generic_attr,
  64. };
  65. static int __init sfi_cpufreq_init(void)
  66. {
  67. int ret, i;
  68. /* parse the freq table from SFI */
  69. ret = sfi_table_parse(SFI_SIG_FREQ, NULL, NULL, sfi_parse_freq);
  70. if (ret)
  71. return ret;
  72. freq_table = kcalloc(num_freq_table_entries + 1, sizeof(*freq_table),
  73. GFP_KERNEL);
  74. if (!freq_table) {
  75. ret = -ENOMEM;
  76. goto err_free_array;
  77. }
  78. for (i = 0; i < num_freq_table_entries; i++) {
  79. freq_table[i].driver_data = i;
  80. freq_table[i].frequency = sfi_cpufreq_array[i].freq_mhz * 1000;
  81. }
  82. freq_table[i].frequency = CPUFREQ_TABLE_END;
  83. ret = cpufreq_register_driver(&sfi_cpufreq_driver);
  84. if (ret)
  85. goto err_free_tbl;
  86. return ret;
  87. err_free_tbl:
  88. kfree(freq_table);
  89. err_free_array:
  90. kfree(sfi_cpufreq_array);
  91. return ret;
  92. }
  93. late_initcall(sfi_cpufreq_init);
  94. static void __exit sfi_cpufreq_exit(void)
  95. {
  96. cpufreq_unregister_driver(&sfi_cpufreq_driver);
  97. kfree(freq_table);
  98. kfree(sfi_cpufreq_array);
  99. }
  100. module_exit(sfi_cpufreq_exit);
  101. MODULE_AUTHOR("Vishwesh M Rudramuni <vishwesh.m.rudramuni@intel.com>");
  102. MODULE_DESCRIPTION("SFI Performance-States Driver");
  103. MODULE_LICENSE("GPL");